1. Field of the Invention
This invention relates broadly to endoscopic instruments. More particularly, this invention relates to endoscopic injection needle devices.
2. State of the Art
An endoscopic injection needle device is inserted through a lumen of a flexible endoscope to inject fluids under endoscopic visualization in body structures such as the esophagus, the stomach, and the colon. For example, during a colonic polypectomy, it is customary to inject saline solution into the tissue surrounding and underlying a polyp in order to raise the polyp to facilitate excision of the polyp by means of an endoscopic forceps or snare. Visible dyes and radiological contrast dyes are sometimes injected to mark the location of areas explored endoscopically so that the structures can be located during subsequent procedures. Additionally, sclerosing agents are sometimes injected into vascular structures, such as esophageal varicoceles, in order to cause clotting and to necrose the tissue so that it can be resorbed by the body.
Typically, an injection needle device consists of a flexible inner tubing (or fluid conduit), usually made of polytetrafluoroethylene (PTFE), surrounded by a loose-fitting outer jacket made of PTFE, fluorinated ethylene propylene (FEP), or similar flexible plastic, a handle assembly at the proximal ends of the inner tubing and outer jacket for relative axial movement thereof, and a needle attached to the distal end of the inner tubing.
In practice, a physician grips the outer jacket of the injection needle device with one hand to introduce it through a sealing port on the endoscope handle which communicates with the working channel of the endoscope and to position the distal end of the device proximate the desired tissue at the distal end of the endoscope. With his or her other hand, the physician holds the proximal handle of the endoscope so that the steering knobs on the endoscope handle can be manipulated while viewing the endoscopic image. The handle assembly of the endoscopic needle device is held and manipulated by an assistant, according to the oral commands of the physician. The assistant moves one component of the handle assembly relative to the other to move the inner tubing axially relative to the outer jacket, thus retracting the needle into the outer jacket or extending it beyond the distal tip of the outer jacket. Once the needle is in position, the assistant then injects a fluid or medicament into the tissue by means of a syringe attached to the handle assembly of the device.
The amount of penetration of the needle into the tissue is not easily controlled by either the physician or the assistant. The depth of penetration of the needle is limited only by the fact that the fluid conduit (or the connector joining the needle point to the fluid conduit) which is larger in diameter than the needle, abuts the tissue. In an alternative procedural method, the physician pushes the jacket up against the tissue, and then the physician orders the assistant to fully advance the needle. In this manner, there is no visualization or degree of control to the penetration of the needle point, except as limited by the abutment of the fluid conduit or connector against the tissue. If the physician determines that a different amount of needle penetration is desired, another device with a needle point of a different length must be used.
While it is customary for a physician to standardize his practice with a needle of a certain penetration length, it sometimes is necessary to inject more superficially, to reduce the possibility of penetrating the tissue structure, or more deeply, to reach a plane of dissection to separate layers of tissue. Therefore, it is necessary to stock several injection needle devices in each gastroenterology suite, each device having a needle with a different length to accommodate the needs of the physician.
A few prior art devices have been built which allow the assistant to control the depth of needle projection beyond the distal end of the jacket, but these devices are imprecise and awkward. For example, the devices described in U.S. Pat. No. 5,380,292 to Wilson and U.S. Pat. No. 4,763,667 to Manzo attempt to achieve a measure of adjustability of the needle projection by utilizing an adjustable stop on the handle assembly of the device. The Wilson and Manzo devices do not have a calibrated control mechanism, and there is no way for the assistant to accurately adjust the depth of needle penetration while the device is in place in the endoscope, because such would require visualization of the needle point and measurement of its projection beyond the distal end of the jacket while turning an adjustment nut. Rather, the Wilson and Manzo devices simply provide a manner by which the device can be prepared prior to use for a specific amount of needle projection. Unfortunately, even the adjustable stop is of limited value, because the design of these prior art devices is such that the length of needle point projection beyond the jacket is highly variable despite the stop. In fact, the position of the needle is strongly influenced by the shape of the endoscope and by forces acting on the needle point. Depending on the degree to which the endoscope is flexed to negotiate the anatomy of the patient, the length of needle projection of most prior art devices is variable because of the various possible positions of the fluid conduit tubing within the loose-fitting outer jacket of the device. Thus, as the device is flexed, the needle point moves relative to the distal end of the jacket. Also, such designs which use a flexible plastic tube for the fluid conduit, are not amenable to precise control of the needle projection, because their needles will retract to some degree, typically a few millimeters, when forced against tissue. That is, the fluid conduit compresses. Thus, these devices do not teach a practicable means of controlling the length of needle projection while the device is being used.
U.S. Pat. No. 5,766,184 to Matsuno et al. describes another needle device having an outer tubular sheath, an inner tubular member extending through the outer tubular sheath and longitudinally and axially rotatably movable relative thereto, a shaft extending through the inner tubular member and coupled to the needle, a needle at the distal end of the inner tubular member, and a handle assembly including a knob which permits axial rotation of the shaft, and therefore the inner tubular member and needle, relative to the sheath. The needle and the distal end of the outer sheath are threadably connected. This threaded connection permits helical rotation of the inner tubular member relative to the outer tubular sheath to cause longitudinal movement of the needle relative to the distal end of the outer tubular sheath. Fluid is injectable through the inner tubular member and the needle into the patient. However, the device has severe drawbacks. It is generally desirable that the pitch of the threads be sufficiently small to permit the fine and precise adjustment of the extension of the needle, e.g., movement of the needle to within a half millimeter. Such fine adjustment requires that the pitch of the thread in the connection preferably be no more than a half millimeter. Yet, this requires that the inner tubular member be rotated a very large number of times relative to the outer tubular member in order to move the needle the required distance. For example, at a pitch of a quarter millimeter, the inner tubular member and outer tubular sheath would need to be completely rotated thirteen times relative to each other in order to effectuate a 6.5 millimeter movement of the needle. Such device operation is impractical for two reasons. First, it is impractical for the physician or assistant to keep count of how many times he or she has rotated the knob which causes the inner tubular member to rotate relative to the outer tubular member. However, keeping count is required as there is no other means by which to determine how far the needle has been extended. As such, absent reliance on the physician""s or assistant""s memory as to how may times the inner tubular member and outer tubular sheath have been rotated relative to each other, it is not possible to determine from the proximal end of the instrument the extension of the needle from the distal end of the instrument. Second, even if the physician or assistant could accurately keep count of the number of rotations, such repetitive rotational movement is uncomfortable, resulting in hand strain. Therefore, this needle device is undesirable to both the physician and the assistant. In addition, the patent fails to adequately describe a handle assembly which can correctly accommodate axial movement of the shaft and inner tubular member relative to the outer sheath as the needle is helically advanced and retracted.
It is therefore an object of the invention to provide an endoscopic needle device having a proximal handle assembly which accurately indicates the extension of the needle from the distal end of the device.
It is another object of the invention to provide an endoscopic needle device which may be conveniently and comfortably operated.
It is a further object of the invention to provide an endoscopic needle device in which the needle is precisely adjustable to deliver different depths of penetration of the needle point while the device is in use.
It is also an object of the invention to provide an endoscopic needle device which precisely controls the position of the needle relative to the distal end of the jacket.
It is an additional object of the invention to provide an endoscopic needle device in which extension of the needle is not affected by such factors as compressibility of the tubular components.
In accord with these objects, which will be discussed in detail below, an endoscopic needle device is provided which includes an inner fluid conduit, an outer sheath extending over the length of the conduit, an elongate longitudinally stiff wire or other element extending through the conduit, and a needle fixedly attached to the distal end of the conduit. The distal end of the wire is coupled to one or both of the needle and the distal end of the conduit. The needle includes a proximal opening such that the hollow of the needle is in fluid communication with a lumen of conduit. A proximal handle assembly includes a stationary member and a movable member longitudinally movable relative to the stationary member. The proximal end of the outer sheath is coupled to the stationary member, and the stationary member includes structure to mount the handle to a port of an endoscope. The movable member includes a passageway, and the proximal end of the conduit is coupled to the distal end of the movable member, and a port, e.g., a luer connector, is provided at the proximal end of the movable member. A syringe may be coupled to the port and operated to inject a fluid (injectate) which travels through the passageway, the lumen of the conduit, and the needle. In addition, the proximal end of the wire is coupled to the movable member. The handle assembly also includes a shaft rotatably coupled to the stationary member, wherein rotation of a knob coupled to the shaft results in reciprocatory (proximal-distal and distal-proximal) movement of the movable member relative to the stationary member, and consequently the needle relative to the distal end of the outer sheath.
According to a first embodiment of the invention, the movable member includes a rack, and the knob is provided with a pinion which engages the rack. Rotation of the knob relative to the stationary member causes the pinion to rotate relative to the movable member, and thus causes reciprocatory movement of the movable member relative to the stationary member which operates to move the position of the needle relative to the distal end of the endoscope. Precise movement is facilitated by the longitudinally stiff wire which extends through the fluid lumen, of the conduit. The wire counters the compressive force to which the conduit is subject when the movable member is moved distally relative to the stationary member. The knob and the stationary member are provided with indicia which indicate the movement of the needle.
According to a second embodiment of the invention, substantially similar to the first embodiment, the conduit is provided with at least two lumina, one for the injectate and the other for the wire. As such, the wire is not in contact with the injectate.
According to a third embodiment of the invention, a gear reduction assembly includes a change gear including two gears of different diameters on a common shaft. The smaller diameter gear engages the rack and the larger diameter gear engages the pinion. The gear reduction assembly permits larger gear teeth to be used on the pinion and rack, thereby facilitating manufacture and assembly of the device.
According to a fourth embodiment of the invention, a rolling band mechanism is utilized to reciprocate the movable member relative to the stationary member. In the rolling band mechanism, a band is wrapped one turn around a shaft attached to the knob, and the ends of the band are held taught at or adjacent ends of the movable member. The band and the shaft frictionally interfere. Rotation of the shaft by the knob causes the shaft to engage the band and results in reciprocal movement of the movable member relative to the stationary member.
According to a fifth embodiment of the invention, the movable member includes a portion provided with a rack, and a screw provided with threads engages the rack. Rotation of a knob portion of the screw causes reciprocatory movement of the movable member relative to the stationary member.
In each embodiment, the position of the knob relative to the housing provides an indication of the extension of the needle. In addition, the longitudinal stiffness of the wire ensures that proximal movement of the conduit relative to the sheath results in like movement of the distal end of the conduit relative to the sheath. As such, the injection needle device of the invention permits controllable movement of the needle such that the needle can be easily, reliably, and precisely advanced and withdrawn.
Additional objects and advantages of the invention will become apparent to those skilled in the art upon reference to the detailed description taken in conjunction with the provided figures.